Vikings safety Harrison Smith is only a 23-year-old rookie. So he doesn't have full perspective on just how encouraging this season's revival has been for an organization that suffered through a 3-13 nightmare in 2011.

But Smith does know enough about the cruel dynamics of the NFL to understand that there's not a huge difference between miserable seasons and invigorating ones.

That's why a Vikings home loss on Sunday would have been harsh, further disintegrating the cheer that had built through the season's first two months.

Instead, with Smith providing a decisive 56-yard interception return touchdown in a 21-14 victory over Chicago, the Vikings still are free to speak the league's magic word -- playoffs -- in mid-December.

And they can do so without a Jim Mora tone of exasperation.

"We still have a chance," Smith said after Sunday's win. "We know every game's a must-win for us. But we're still in the thick of things. And the playoffs are still a real possibility."

Video (58:26): Frazier: Ponder facing 'defining moment'

At this point, staring at the NFL standings and trying to decipher a clear postseason picture is more difficult than detecting a 3D schooner in one of those 1990s "Magic Eye" drawings.

Ten NFC teams are at .500 or above, including the Vikings and their opponent on Sunday, St. Louis.

Three weeks remain.

So what would it take for the Vikings to stretch their heartening season into January?

It's a tricky equation, with the Vikings having control over only three of the league's final 48 games.

But the Vikings do realize their chase of a playoff berth likely will require victories at St. Louis and Houston plus a home upset of Green Bay in the finale. (They're certain to be underdogs in all three games.)

But say the Vikings get hot, win out and finish 10-6. Would that be enough to push through the playoff gates?

Winning the division

Because of tiebreaker scenarios, Green Bay can clinch the NFC North as early as Sunday with a victory at Chicago. And it's worth noting that the Packers have owned the Bears in recent years, winning seven of the past eight meetings.

But the Vikings' window of opportunity to steal the division title could open if Chicago beats Green Bay.

If that happens and the Vikings finish tied at 10-6 with the Packers or Bears (or both) -- which would necessarily include head-to-head splits and matching 4-2 NFC North records -- the third tiebreaker would be winning percentage against common opponents.

The Vikings, Packers, and Bears have eight common opponents outside the division: San Francisco, Seattle, Indianapolis, St. Louis, Houston, Jacksonville, Arizona and Tennessee.

Green Bay and Chicago are 4-3 against those foes, and both could improve to 5-3. The Vikings are 4-2 against those opponents and would improve to 6-2 if they won out. In either a two- or three-way tie, that common opponents record would give the Vikings the NFC North title.

Back-door cuts

The wild-card chase is considerably more complicated.

The Seahawks (8-5) occupy the top wild-card slot with Chicago (8-5) right behind.

The Giants also are 8-5 but lead the NFC East. However, the Redskins and Cowboys, both 7-6, are in hot pursuit in the division race with both eyeing a possible wild-card berth as well.

With so many games and potential outcomes left, attempting to explain every possible final-record scenario would be futile.

(On the bright side, ESPN.com has installed a Playoff Machine for those interested in testing every possible combination of results.)

But ultimately, it seems inevitable that on the afternoon of Dec. 30, the NFL's tiebreaking procedures will be ready for application -- from head-to-head results, to conference records, to games against common opponents, to strength of victory and strength of schedule.

In the meantime, Vikings coach Leslie Frazier continues taking cursory glances at the standings, just for confirmation his team is still in the mix.

"I'm aware of where we are for sure," Frazier said Wednesday. "Made our team aware as well."

But he also sees the cluttered mess in the NFC and knows he has only one way to translate it.

"The most important thing for us is concentrating on St. Louis," Frazier said. "We have to win this game. If we don't win this game, it puts us in peril. I've tried to bring the focus to that -- without ignoring that we're in a playoff race."

Jeff Wheeler, Star Tribune

In order to have a chance at the playoffs, Vikings coach Leslie Frazier knows his team must win on the road — starting Sunday at St. Louis. “I’m aware of where we are for sure,” he said. “Made our team aware as well.”